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[108.223.40.66]) by smtp.gmail.com with ESMTPSA id x24sm2099614pgl.84.2019.08.23.07.19.30 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 23 Aug 2019 07:19:31 -0700 (PDT) Date: Fri, 23 Aug 2019 07:19:30 -0700 From: Guenter Roeck To: Ivan Mikhaylov Cc: Wim Van Sebroeck , Joel Stanley , Andrew Jeffery , linux-watchdog@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-aspeed@lists.ozlabs.org, linux-kernel@vger.kernel.org, Alexander Amelkin , openbmc@lists.ozlabs.org Subject: Re: [PATCH v1 3/3] watchdog/aspeed: add support for dual boot Message-ID: <20190823141930.GA11610@roeck-us.net> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Aug 23, 2019 at 12:35:28PM +0300, Ivan Mikhaylov wrote: > Set WDT_CLEAR_TIMEOUT_AND_BOOT_CODE_SELECTION into WDT_CLEAR_TIMEOUT_STATUS > to clear out boot code source and re-enable access to the primary SPI flash > chip while booted via wdt2 from the alternate chip. > > AST2400 datasheet says: > "In the 2nd flash booting mode, all the address mapping to CS0# would be > re-directed to CS1#. And CS0# is not accessable under this mode. To access > CS0#, firmware should clear the 2nd boot mode register in the WDT2 status > register WDT30.bit[1]." > > Signed-off-by: Ivan Mikhaylov > --- > drivers/watchdog/aspeed_wdt.c | 44 ++++++++++++++++++++++++++++++++++- > 1 file changed, 43 insertions(+), 1 deletion(-) > > diff --git a/drivers/watchdog/aspeed_wdt.c b/drivers/watchdog/aspeed_wdt.c > index cc71861e033a..62bf95cb741f 100644 > --- a/drivers/watchdog/aspeed_wdt.c > +++ b/drivers/watchdog/aspeed_wdt.c > @@ -53,6 +53,8 @@ MODULE_DEVICE_TABLE(of, aspeed_wdt_of_table); > #define WDT_CTRL_ENABLE BIT(0) > #define WDT_TIMEOUT_STATUS 0x10 > #define WDT_TIMEOUT_STATUS_BOOT_SECONDARY BIT(1) > +#define WDT_CLEAR_TIMEOUT_STATUS 0x14 > +#define WDT_CLEAR_TIMEOUT_AND_BOOT_CODE_SELECTION BIT(0) > > /* > * WDT_RESET_WIDTH controls the characteristics of the external pulse (if > @@ -165,6 +167,42 @@ static int aspeed_wdt_restart(struct watchdog_device *wdd, > return 0; > } > > +/* access_cs0 shows if cs0 is accessible, hence the reverted bit */ > +static ssize_t access_cs0_show(struct device *dev, > + struct device_attribute *attr, char *buf) > +{ > + struct aspeed_wdt *wdt = dev_get_drvdata(dev); > + Unnecessary empty line. > + uint32_t status = readl(wdt->base + WDT_TIMEOUT_STATUS); > + > + return sprintf(buf, "%u\n", > + !(status & WDT_TIMEOUT_STATUS_BOOT_SECONDARY)); > +} > + > +static ssize_t access_cs0_store(struct device *dev, > + struct device_attribute *attr, > + const char *buf, size_t size) > +{ > + struct aspeed_wdt *wdt = dev_get_drvdata(dev); > + unsigned long val = 0; Unnecessary initialization. > + > + if (kstrtoul(buf, 10, &val)) > + return -EINVAL; > + > + if (val) > + writel(WDT_CLEAR_TIMEOUT_AND_BOOT_CODE_SELECTION, > + wdt->base + WDT_CLEAR_TIMEOUT_STATUS); > + > + return size; > +} > +static DEVICE_ATTR_RW(access_cs0); > + > +static struct attribute *bswitch_attrs[] = { > + &dev_attr_access_cs0.attr, The attribute needs to be documented. > + NULL > +}; > +ATTRIBUTE_GROUPS(bswitch); > + > static const struct watchdog_ops aspeed_wdt_ops = { > .start = aspeed_wdt_start, > .stop = aspeed_wdt_stop, > @@ -306,8 +344,12 @@ static int aspeed_wdt_probe(struct platform_device *pdev) > } > > status = readl(wdt->base + WDT_TIMEOUT_STATUS); > - if (status & WDT_TIMEOUT_STATUS_BOOT_SECONDARY) > + if (status & WDT_TIMEOUT_STATUS_BOOT_SECONDARY) { > wdt->wdd.bootstatus = WDIOF_CARDRESET; > + wdt->wdd.groups = bswitch_groups; > + } So the attribute would only exist if the boot was from the secondary flash, and it would exist even if it wasn't needed (ie on ast2500 / ast2600) ? Well, if that is what you want, who am I to argue, but you'll have to document it accordingly. When you do so, please also document what happens on ast2500 / ast2600 when the attribute exists and is written. > + > + dev_set_drvdata(dev, wdt); > > return devm_watchdog_register_device(dev, &wdt->wdd); > } > -- > 2.20.1 > >